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Ultrasound Obstet Gynecol. 2019 Jul 4. doi: 10.1002/uog.20389. [Epub ahead of print]

Learning curves of open and endoscopic fetal spina bifida closure: a systematic review and meta-analysis.

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Department of Development and Regeneration, Cluster Organ Systems, Biomedical Sciences, Faculty of Medicine, Catholic University of Leuven, Leuven, Belgium.
Center for Surgical Technologies, Faculty of Medicine, KU Leuven, Leuven, Belgium.
Center for Fetal Diagnosis and Treatment, the Children's Hospital of Philadelphia, and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Obstetrics and Gynecology, Division Woman And Child, Fetal Medicine Unit, University Hospital of Leuven, Leuven, Belgium.
Department of Mechanical Engineering, KU Leuven, Leuven, Belgium.
Department of Fetal Medicine, The Heart Hospital, São Paulo, Brazil; Department of Fetal Medicine Pro Matre Hospital, São Paulo, Brazil.
Neuroscience Institute, The Heart Hospital, University of São Paulo, São Paulo, Brazil.
Department of Descriptive and Topografic Anatomy, Medical University of Silesia in Katowice, School of Medicine with Division of Dentistry, Zabrze, Poland.
Department of Gynecology, Obstetrics and Gynecologic Oncology in Bytom, Medical University of Silesia, Bytom, Poland.
Department of Obstetrics and Gynecology, Sinai Health System, Mount Sinai Hospital, Toronto, Ontario, Canada.
Department of Pediatric Surgery, Great Ormond Street Hospital, University College London Hospitals NHS Foundation trust, London, United Kingdom.
Department of Neurosurgery, Baylor College of Medicine, and Texas Children's Fetal Center, Houston, Texas, USA.
Department of Obstetrics and Gynecology, Baylor College of Medicine, and Texas Children's Fetal Center, Houston, Texas, USA.
Fetal Therapy Center, Hospital Israelita Albert Einstein, São Paulo, Brazil.
Department of Obstetrics and Gynecology, Taubate University, São Paulo, Brazil.
Fetal Care and Treatment Center, UC Davis Children's Hospital, Sacramento, California, USA.
Department of Neurosurgery, University Hospital of Leuven, Leuven, Belgium.
Institute of Women's Health, University College London Hospitals, London, United Kingdom.



The Management Of Myelomeningocele Study (MOMS) trial demonstrated the safety and efficacy of open fetal surgery for spina bifida (SB). Recently developed alternative techniques may reduce maternal risks yet should do without compromising on fetal neuroprotective effects. We aimed to assess the learning curve of different fetal SB closure techniques.


We searched Medline, Web of Science, Embase, Scopus and Cochrane databases and the grey literature to identify relevant articles without language restriction from January 1980 until October 2018. We systematically reviewed and selected studies reporting all consecutive procedures and with a postnatal follow-up ≥12 months. They also had to report outcome variables necessary to measure the learning curve defined by fetal safety and efficacy. Two independent authors retrieved the data, assessed the quality of the studies and categorized observations into blocks of 30 patients. For meta-analysis, data were pooled using a random-effect model when heterogeneous. To measure the learning curve, we used two complementary methods. With the group splitting method, competency was defined when the procedure provided comparable results to the MOMS trial for 12 outcome variables representative for (1) the immediate surgical outcome, (2) short-term neonatal neuroprotection and (3) long-term neuroprotection at ≥12 months. Then, when the patients' raw data were available, we performed cumulative sum (CUSUM) analysis based on a composite binary outcome defining a successful surgery. It combined four clinically relevant variables for safety (fetal death within 7 days) and for efficacy (neuroprotection at birth).


We included 17/6024 (0.3%) studies with low and moderate risks of bias. Fetal SB closure was performed via standard-hysterotomy (n=11), mini-hysterotomy (n=1) or fetoscopy [exteriorized-uterus single-layer (n=1), percutaneous single-layer (n=3) or percutaneous two-layer closure (n=1)]. Only outcomes for the standard-hysterotomy could be meta-analyzed. Overall, outcomes significantly improved with experience. Competency was reached after 35 consecutive cases for standard-hysterotomy and was predicted to be achieved after ≥57 cases for mini-hysterotomy and ≥56 for percutaneous two-layer fetoscopy. For percutaneous and uterus-exteriorized single-layer fetoscopy, competency was not respectively reached by cases 81 and 28 available for analysis.


The number of cases operated correlates with the outcome of SB fetal closure and ranges from 35 cases for standard-hysterotomy to ≥56-57 cases for minimally invasive modifications. Our observations provide important information for institutions eager to establish a new fetal center, develop a new technique or train their team, and inform referring clinicians, potential patients and third-parties. This article is protected by copyright. All rights reserved.


Spina bifida; fetal surgery; fetoscopy; learning curve; meta-analysis; myelomeningocele; open fetal surgery; systematic review


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